Meadowmist, it is probably worth buying EQ. The hardest thing (I think) is designing quilts with different block sizes, but if you can combine the units so that (4) 4" blocks makes an 8" pattern, that's pretty easy. I still do a lot with graph paper, colored bits (usually from junk mail) and messing around with stuff physically as well as mentally, Graph paper is easier to handle while watching tv!
When I started quilting it was back in the 70s... I had a number of things I used to help my mental planing, not sure what they are called today but various "tray" puzzles for long car drives? Tiles of shapes and colors. Some of wood or plastic or magnets.. Tangram is a special type, but stuff like this is great
https://en.wikipedia.org/wiki/Tangram
Then this classic book came out
https://www.amazon.com/Log-Cabin-Qui.../dp/0960297014
I still use it to refer to different layouts.
But for the ease of project planing, you can fuzz your eyes and mind and treat log cabin blocks exactly the same as HST (half-square triangle) squares, keeping in mind that those little tiles equal whatever size you are working with.